This invention relates to a method and apparatus for testing welds, and, more particularly, to the testing of welds by use of pressurized air.
In the construction of ships and other vessels, openings are typically provided in a structural member to allow one member to pass through another member at the opening. These openings are usually larger than necessary to provide for slight variations in construction, i.e., variations in spacing and height. Once the members are in place the openings are typically closed by using a collar, which can be of a variety of configurations, such as a collar which fits into the opening, or a collar that overlaps at least part of the structural member. The latter is called a lap collar. While the lap collar generally has certain advantages over the other types of collars, it will be seen that the lap collar of the present invention has the additional advantage of permitting the testing of the welded connection between a number of collars and longitudinal members along the entire length of a web.
Regardless of the collar being used, it is critical that certain welded boundary connections be leak free in order to prevent both the contamination of cargo and the leakage of cargo to ballast tanks. Extensive testing of these welds for leaks is thus required.
This inspection and testing process is typically conducted after the final construction of the vessel and while the vessel is in dry dock. A tank or compartment is pressurized in the range of two to five pounds per square inch (p.s.i.), with a soap solution applied to the boundary welds on the outside of the tank. Leaks through the welds form bubbles, which are easily observed. The leaks are then marked and repaired.
Because this procedure is conducted at a late stage in the vessel construction, the test is cumbersome to perform. Furthermore, it is often difficult to gain access to the faulty welds, adding to the repair time and expense. It would be desirable to conduct inspection tests during the assembly stage of construction and under highly controlled conditions. Additionally, a test using highly pressurized air will identify more defects in the welds than the prior art low pressure tank method
Accordingly, the objects of the present invention are to provide the following:
a) An improved collar structure for ships;
b) An improved structure and method for testing of welds on ships;
c) An improved structure and method for conducting oiltight and watertight boundary weld tests using pressurized air; and
d) An improved structure and method for the testing of welds at intermediate stages of the vessel construction.
Other objects and advantages of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings.